Novel method and system for softening sewage and synchronously removing silicon

Abstract

The invention discloses a novel sewage softening and silicon removal synchronous method and system. The method comprises the following steps: detecting the concentration of calcium ions and the concentration of silicon dioxide in wastewater; adjusting the pH value of the wastewater; adjusting the temperature of the wastewater; adding a sodium hydroxide agent into the wastewater and stirring; and carrying out solid-liquid separation to obtain treated wastewater. According to the method, a chemical precipitation method is adopted, a sodium hydroxide agent is added into the high-calcium and high-silicon-dioxide wastewater, and a calcium silicate precipitate is generated through a chemical reaction, so that the aim of removing calcium ions and silicon dioxide is synchronously achieved, and the dual effects of sewage softening and silicon removal are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to a novel sewage softening and synchronous silicon removal method and system, which is particularly suitable for treating high-calcium and high-silicon dioxide wastewater. Background Art

[0002] With the continuous development of industrial production, the problem of wastewater discharge is becoming increasingly serious. In many industries, such as chemical, metallurgical, and electric power, the wastewater produced often contains a large amount of calcium ions and silica. High-calcium wastewater can cause scaling of pipes and equipment, affecting the normal operation and service life of equipment and increasing maintenance costs. If the silica in the wastewater is discharged without effective treatment, it will damage the ecological environment of the water body, affect the water quality, and may cause membrane pollution and other problems in the subsequent water treatment process, increasing the difficulty and cost of treatment.

[0003] Traditional sewage treatment processes often separate softening and silicon removal. The process is complicated and requires multiple treatment units, which not only occupies a large area but also has high treatment costs. At the same time, some existing silicon removal methods have problems such as low silicon removal efficiency, strict requirements on water quality, or the introduction of new pollutants. Therefore, it is urgent to develop an efficient, economical and environmentally friendly sewage softening and simultaneous silicon removal process. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0005] To this end, an embodiment of the present invention provides a novel sewage softening and simultaneous silicon removal method.

[0006] In the first aspect, the present invention proposes a novel sewage softening and simultaneous silicon removal method, comprising the following steps:

[0007] (a) Detecting the calcium ion concentration and silicon dioxide concentration in wastewater;

[0008] (b) adjusting the pH value of wastewater;

[0009] (c) regulating the temperature of wastewater;

[0010] (d) adding sodium hydroxide reagent to the wastewater and stirring;

[0011] (e) Solid-liquid separation to obtain treated wastewater.

[0012] Furthermore, in the step (b), the pH value of the wastewater is adjusted to 10-12.

[0013] Furthermore, in the step (c), the temperature of the wastewater is adjusted to 30-40°C.

[0014] Furthermore, in the step (c), the wastewater is treated with a heat exchanger to adjust the temperature of the wastewater.

[0015] Furthermore, in the step (d), the amount of sodium hydroxide reagent added is determined according to the calcium ion concentration and the silicon dioxide concentration.

[0016] Furthermore, when the calcium ion concentration in the wastewater is between 500 and 2000 mg / L and the silicon dioxide concentration is between 100 and 500 mg / L, the amount of sodium hydroxide added is 5 to 15 g / L.

[0017] Furthermore, in step (e), the calcium ion concentration of the treated wastewater is reduced to below 50 mg / L, and the silicon dioxide is reduced to below 50 mg / L.

[0018] On the other hand, the present invention proposes a novel sewage softening and simultaneous silicon removal system, which is used to implement the method proposed in the first aspect, comprising:

[0019] A detection unit, the detection unit is used to detect the calcium ion concentration and the silicon dioxide concentration in the wastewater before and after treatment;

[0020] A pH value adjusting unit, wherein the pH value adjusting unit is used to adjust the pH value of the wastewater;

[0021] A heat exchange unit, wherein the heat exchange unit is used to adjust the temperature of the wastewater;

[0022] A reagent dosing unit, wherein the reagent dosing unit is used to add reagents to the wastewater;

[0023] A solid-liquid separation unit, the solid-liquid separation unit is used to separate the treated wastewater

[0024] Furthermore, the pH value adjusting unit includes a pH meter and a pH adjusting agent storage tank.

[0025] Furthermore, the heat exchange unit heats or cools the wastewater by heat exchange.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] The present invention adopts a chemical precipitation method, by adding sodium hydroxide reagent to high-calcium and high-silicon dioxide wastewater, using chemical reaction to generate calcium silicate precipitation, thereby simultaneously achieving the purpose of removing calcium ions and silicon dioxide, and achieving the dual effects of sewage softening and silicon removal. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0029] Figure 1It is a schematic diagram of the process of the novel sewage softening and simultaneous silicon removal method of the present invention;

[0030] Figure 2 It is a schematic diagram of the novel sewage softening and simultaneous silicon removal system of the present invention. DETAILED DESCRIPTION

[0031] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0032] The following describes the novel sewage softening and simultaneous silicon removal method and system proposed by the present invention in conjunction with the accompanying drawings.

[0033] like Figure 1 As shown, the novel sewage softening and simultaneous silicon removal method of the present invention comprises the following steps:

[0034] (a) Detecting the calcium ion concentration and silicon dioxide concentration in wastewater;

[0035] (b) adjusting the pH value of wastewater;

[0036] (c) regulating the temperature of wastewater;

[0037] (d) adding sodium hydroxide reagent to the wastewater and stirring;

[0038] (e) Solid-liquid separation to obtain treated wastewater.

[0039] In step (a), the hardness and silicon content of the wastewater are preliminarily determined by detecting the calcium ion concentration and silicon dioxide concentration in the wastewater to determine the amount of treatment agent to be added.

[0040] In step (b), the pH value of the wastewater is adjusted to 10-12. After a large number of experimental studies and data analysis, the optimal pH range of the process is 10-12. When the pH value is lower than 10, the reaction rate of silicon dioxide and hydroxide ions is slow, and the amount of silicate ions generated is small, which is not conducive to the formation of calcium silicate precipitation, resulting in poor silicon removal and softening effects. When the pH value is higher than 12, although the reaction of silicon dioxide will be more sufficient, the excessively high alkaline environment may cause some metal ions (such as aluminum ions, etc.) to form soluble hydroxyl complexes, interfering with the subsequent precipitation process, and the difficulty and cost of treating highly alkaline wastewater will also increase. In actual operation, the pH value of the wastewater can be monitored in real time by a pH meter, and an appropriate amount of hydrochloric acid (HCl) or sodium hydroxide solution can be used for adjustment to ensure that the pH value of the reaction system is stable within the optimal range.

[0041] In step (c), the temperature of the wastewater is adjusted to 30-40°C. In this temperature range, the chemical reaction rate is relatively fast, which can ensure that the reaction between silicon dioxide and hydroxide ions and the formation of calcium silicate precipitation are relatively rapid and complete. When the temperature is lower than 30°C, the chemical reaction rate decreases, the precipitation generation rate slows down, the treatment efficiency will be significantly reduced, and a longer reaction time may be required to achieve the desired removal effect. When the temperature is higher than 40°C, on the one hand, some volatile substances in the wastewater may volatilize, affecting the treatment environment; on the other hand, too high a temperature may increase the corrosiveness of the sodium hydroxide solution and cause damage to the equipment.

[0042] In some embodiments, the wastewater is heated or cooled by a heat exchanger or other equipment.

[0043] In step (d), sodium hydroxide is added to the wastewater and stirred for reaction. Sodium hydroxide is completely ionized in water to produce sodium ions (Na + ) and hydroxide ions (OH - ), its ionization equation is: NaOH=Na + +OH - .

[0044] Silica (SiO2) in wastewater is an acidic oxide that reacts with hydroxide ions (OH - ) reacts. Under certain conditions, silicon dioxide reacts with hydroxide ions to form silicate ions (SiO3 2- ) and water, the reaction equation is: SiO2+2OH - =SiO3 2- +H2O.

[0045] Then, the calcium ions (Ca 2+ ) and the generated silicate ions (SiO3 2- ) combine to produce a precipitation reaction, forming calcium silicate (CaSiO3) precipitation. The reaction equation is: Ca 2+ +SiO3 2- =CaSiO3↓. Through this series of chemical reactions, calcium ions and silicon dioxide are removed from wastewater in the form of precipitation.

[0046] The amount of sodium hydroxide added is determined according to the calcium ion concentration and the silicon dioxide concentration. When the calcium ion concentration in the wastewater is between 500 and 2000 mg / L and the silicon dioxide concentration is between 100 and 500 mg / L, the amount of sodium hydroxide added is 5 to 15 g / L.

[0047] In practical applications, when the concentration of calcium and silicon dioxide in wastewater is too high, the amount of sodium hydroxide can be appropriately increased, but excessive addition should be avoided. Excessive sodium hydroxide will not only cause reagent waste and increase treatment costs, but also make the treated wastewater too alkaline, requiring more acid to neutralize. In practical applications, small-scale experiments can be conducted first to accurately determine the optimal amount of sodium hydroxide to be added based on the specific content of calcium and silicon dioxide in the wastewater.

[0048] In step (e), solid-liquid separation is performed to obtain treated wastewater, and the calcium ion concentration and silicon dioxide concentration of the treated wastewater can be detected to verify the treated wastewater.

[0049] In some embodiments, after the reaction is completed, solid-liquid separation is performed by precipitation and filtration.

[0050] In some embodiments, the calcium ion concentration of the treated wastewater is reduced to below 50 mg / L, and the removal rate of calcium ions can reach more than 95%. The silica is reduced to below 50 mg / L, and the removal rate of silica can reach more than 90%. The high-calcium and high-silicon dioxide wastewater treated by this process has a significant removal effect and can meet the sewage discharge standard. Moreover, the generated calcium silicate precipitate is stable in nature and can be easily separated from the wastewater by conventional solid-liquid separation methods such as precipitation and filtration, and will not cause secondary pollution to the environment. At the same time, in the process of removing calcium and silica, the process also has a certain synergistic removal effect on other impurities in the wastewater, such as some heavy metal ions, suspended matter, etc., which helps to improve the overall water quality of the wastewater.

[0051] The method of the present invention achieves efficient treatment of high-calcium and high-silicon dioxide wastewater through a unique chemical precipitation reaction and precise control of process parameters, bringing new technological breakthroughs to the field of sewage treatment and having important economic and environmental benefits.

[0052] The new sewage softening and simultaneous silicon removal system is used to implement the new sewage softening and simultaneous silicon removal method, such as Figure 2 As shown, it includes a detection unit, a pH value adjusting unit, a heat exchange unit, a reagent dosing unit and a solid-liquid separation unit. The detection unit is used to detect the calcium ion concentration and the silica concentration in the wastewater before and after treatment, the pH value adjusting unit is used to adjust the pH value of the wastewater, the heat exchange unit is used to adjust the temperature of the wastewater, the reagent dosing unit is used to add reagents to the wastewater, and the solid-liquid separation unit is used to separate the treated wastewater.

[0053] In some embodiments, the pH value adjusting unit includes a pH meter and a pH adjusting agent storage tank, and the amount and type of adjusting agent added to the pH adjusting agent storage tank are controlled according to the value of the pH meter. In some embodiments, the pH adjusting agent storage tank includes a hydrochloric acid storage tank and a sodium hydroxide solution storage tank, and when the pH value of the wastewater is lower than 10, sodium hydroxide solution is added for adjustment, and when the pH value of the wastewater is higher than 12, hydrochloric acid solution is added for adjustment.

[0054] In some embodiments, the heat exchange unit heats or cools the wastewater by heat exchange. It is understandable that when the temperature of the wastewater is low, the wastewater acts as a heat sink to absorb heat from a heat source in the heat exchanger, where the heat source may be high-temperature water or other high-temperature medium; when the temperature of the wastewater is high, the wastewater acts as a heat source to release heat to a heat sink in the heat exchanger, where the heat sink may be low-temperature water or other low-temperature medium.

[0055] The present invention is described below with reference to specific embodiments.

[0056] Embodiment 1:

[0057] Take 10L of high-calcium and high-silicon dioxide wastewater discharged by a chemical company. After testing, its initial calcium ion concentration is 1000mg / L, the silica concentration is 200mg / L, the pH value is 8.5, and the temperature is 25°C. First, add an appropriate amount of sodium hydroxide solution to the wastewater to adjust the pH value to 10. Then, the wastewater temperature is raised to 30°C through a heat exchanger. Next, add 50g of sodium hydroxide to the wastewater and stir the reaction for 60min to allow the agent to fully react with the calcium and silica in the wastewater. After the reaction, precipitation and filtration methods are used for solid-liquid separation. After testing, the calcium ion concentration in the treated wastewater is 30mg / L and the silica concentration is 40mg / L, achieving a good treatment effect.

[0058] Example 2

[0059] Take 10L of high-calcium and high-silicon dioxide wastewater produced by a metallurgical plant, with an initial calcium ion concentration of 1500mg / L, a silica concentration of 300mg / L, a pH value of 9.0, and a temperature of 35°C. First, add an appropriate amount of sodium hydroxide solution to the wastewater to adjust the pH value to 11. Then, add 60g of sodium hydroxide to the wastewater and stir the reaction for 45min. After the reaction is completed, precipitation and filtration operations are performed. After testing, the calcium ion concentration in the treated wastewater is 40mg / L and the silica concentration is 30mg / L, achieving a good treatment effect.

[0060] It can be seen from the above embodiments that the novel sewage softening and simultaneous silicon removal process method of the present invention has the advantages of simple operation, good treatment effect, low cost, etc., has broad application prospects, and can provide an efficient and reliable technical solution for the treatment of high-calcium and high-silicon dioxide wastewater.

[0061] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms may be for different embodiments or examples. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0062] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0063] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A novel sewage softening and simultaneous silicon removal method, characterized in that: include: (a) Detecting the calcium ion concentration and silicon dioxide concentration in wastewater; (b) adjusting the pH value of wastewater; (c) regulating the temperature of wastewater; (d) adding sodium hydroxide reagent to the wastewater and stirring; (e) Solid-liquid separation to obtain treated wastewater.

2. The method according to claim 1, characterized in that In the step (b), the pH value of the wastewater is adjusted to 10-12.

3. The method according to claim 1, characterized in that In the step (c), the temperature of the wastewater is adjusted to 30-40°C.

4. The method according to claim 1, characterized in that In the step (c), the wastewater is treated by a heat exchanger to adjust the temperature of the wastewater.

5. The method according to claim 1, characterized in that In the step (d), the amount of sodium hydroxide reagent added is determined according to the calcium ion concentration and the silicon dioxide concentration.

6. The method according to claim 5, characterized in that When the calcium ion concentration in the wastewater is between 500 and 2000 mg / L and the silicon dioxide concentration is between 100 and 500 mg / L, the amount of sodium hydroxide added is 5 to 15 g / L.

7. The method according to claim 1, characterized in that In the step (e), the calcium ion concentration of the treated wastewater is reduced to below 50 mg / L, and the silicon dioxide concentration is reduced to below 50 mg / L.

8. A new type of sewage softening and synchronous silicon removal system, characterized in that: The method for implementing any one of claims 1 to 7 comprises: A detection unit, the detection unit is used to detect the calcium ion concentration and the silicon dioxide concentration in the wastewater before and after treatment; A pH value adjusting unit, wherein the pH value adjusting unit is used to adjust the pH value of the wastewater; A heat exchange unit, wherein the heat exchange unit is used to adjust the temperature of the wastewater; A reagent dosing unit, wherein the reagent dosing unit is used to add reagents to the wastewater; A solid-liquid separation unit is used to separate the treated wastewater.

9. The system according to claim 8, characterized in that The pH value adjusting unit comprises a pH meter and a pH adjusting agent storage tank.

10. The system according to claim 8, characterized in that The heat exchange unit heats or cools the wastewater by heat exchange.

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